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Hakoda, Teruyuki; Igarashi, Hidetoshi*; Isozumi, Yukihiro*; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
Journal of Physics and Chemistry of Solids, 74(2), p.200 - 204, 2013/02
Times Cited Count：3 Percentile：16.73(Chemistry, Multidisciplinary)The gasochromic property of dehydrogenation-catalyst loaded tungsten trioxide (M/WO
) powders was examined in exposure to gaseous cyclohexane under different kinds and contents of catalysts, catalyst temperatures, and cyclohexane concentrations. The change in the intensity of visible lights reflected from the M/WO powders was in situ obtained using a portable visible-light spectrometer. The catalyst of Pt was a catalyst initiating dehydrogenation and the change of reflected light intensity at lower temperatures in comparison with the catalysts of Pd and Rh. Among 0.1, 0.5, and 1wt% Pt/WO powders, the 0.5wt% Pt/WO powders demonstrated large change of reflected lights. The heating of 0.5wt% Pt/WO powders at temperatures higher than 130
C was required to visually detect cyclohexane at a concentration of 1v%, lower than the combustion lower limit (1.3v%).
Isozumi, Yukihiro; Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
Radioisotopes, 61(6), p.289 - 296, 2012/06
In the present study, the reduction of PtCl
ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 1-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as primary particles through reduction of PtCl ions. Moreover, these Pt particles were observed to have hydrogen dissociation activity and oxidation activity.
Isozumi, Yukihiro; Suzuki, Ryuta*; Hakoda, Teruyuki; Yoshikawa, Masahito; Aritani, Hirofumi*
no journal, ,
The organic hydrides has been focused as a substance that stores and transports hydrogen safely, therefore the optical sensor to detect its leakage has been needed for its flammability. In recent studies, some kind of dehydrogen metals over WO gasochromic substrate have been developed for the sensor, but dehydro-mechanism over these metals was not clear because WO absorb hydrogen produced through dehydrogenation. In the present study, the dehydrogen reaction over these metals was evaluated by comparing the dehydrogen activity over catalyst metals over different substrates including WO. It was confirmed that Pt had a dehydro-activity at the lowest reaction temperature and produced the amount of benzene was equal to that of consumed cyclohexane stoichiometrically. Sintering of Pt over the WO substrate also caused deactivation gradually up to 125C.
Igarashi, Hidetoshi; Hakoda, Teruyuki; Isozumi, Yukihiro; Tezuka, Meguru*; Yamamoto, Shunya; Yoshikawa, Masahito
no journal, ,
The coloration and dehydrogenation property of dehydrogen metal-catalyst loaded tungsten trioxide (M/WO) powders were examined for gaseous cyclohexane under different catalyst temperatures and cyclohexane concentrations to develop gasochromic materials to detect organic hydrides for hydrogen storage. The change in the color of the M/WO powder in a glass reactor was in situ examined using a portable spectrometer with contacting with cyclohexane gases under different powder temperatures. For 5% cyclohexane, the coloration of 0.5wt% Pt/WO was initiated at the lowest catalyst temperature of 100C as compared with 140C for 0.5wt% Pd/WO and 150C for 0.5wt% Rh/WO. The coloration of 0.5wt% Pt/WO was also initiated for cyclohexane at concentration of 1%, lower than the combustion lower limit (1.3%), by heating at a temperature of 170C.
Isozumi, Yukihiro; Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
We confirmed reduction of Pt ion, preparation of particles and catalytic activity of these particles in 10mL solution including 5mM Pt ion and ethanol induced by low energy electron beam(EB) irradiation that has a high dose rate to confirm the availability of radiation induced reduction using low energy EB for one kind of method, it prepare noble metal particles having catalytic activity. The maximum dose of Pt particles was shown in a 10% ethanol. Diameters of these Pt particles that were produced in this irradiated solution were mostly 2 to 5nm, and a part of these particles coagulated each other to become particles with sizes of a few tens to a few hundred nm. The fact these Pt particles has a hydrogen dissociation catalytic ability was induced by the coloration of tungsten trioxide, which is one of hydrogen gasochromic materials. These results suggest that low energy EB irradiation is applicable method for preparation fine noble metal particles having catalytic activity.
Hakoda, Teruyuki; Isozumi, Yukihiro*; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
In the present study, the reduction of PtCl
ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 5-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as a primary particle through reduction of PtCl ions. Moreover, these Pt particles was observed to have hydrogen dissociation activity and oxidation activity.
Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito; Isozumi, Yukihiro*; Aritani, Hirofumi*
no journal, ,
In the present study, the reduction of PtCl ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 1-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as primary particles through reduction of PtCl ions. Moreover, these Pt particles were observed to have hydrogen dissociation activity and oxidation activity.
